I usually only post 15% or higher down days. But that can be relative to the price. If it is a really high priced stock a 10% drop is significant. I never play ex-divy for a bounce - tried it years ago and it just didn't work for me. A divy payment isn't always a guarantee of a drop. And they don't always spring up quickly when they do drop. Go here and try doing it as a paper trade for a few weeks and see how you do: https://www.thestreet.com/dividends/index.html